Water in the boot

[dogsridewith]

There is a joint in the overlapping spot welded tin where the gutter dumps rearward (above the taillights). I also cleaned up that area when I did the taillight gasket...but didn't add caulk or anything up there. The gutters themselves are smooth and crack free.
I still get dripping from the hatch raised some time after a rain, as if water got into it...starting to wonder about small shields at hatch top corners trapping water and letting it into the hatch through the holes for the clips.